Synchronizing the movement of first and second articles and printing markings on one of the articles

ABSTRACT

In synchronizing the movement of first and second articles, such as an elongated strand (jacketed cable) and a rotatable printing wheel mechanism for printing markings on the strand at accurately spaced intervals, the printing wheel mechanism is rotatably driven by a variable speed drive mechanism. The variable speed drive mechanism. The variable speed drive mechanism and a strand advancing mechanism drive respective signal generating devices, the signals of which are compared to produce a coarse analogue control signal representative of any difference therebetween. Similarly, the variable speed drive mechanism and a rotatable control member which is rotatably driven through frictional engagement with the advancing strand, drive digital signal generating devices, the signals of which are compared and used to produce an overriding fine analogue control signal representative of any difference between them. The coarse and fine analogue control signals then are combined to produce a signal for controlling the speed of the variable speed drive mechanism, and thus of the printing wheel mechanism.

United States Patent 72 Inventor Robert F. Miuehart 3,288,336 11/1966 Smith 226/30X l 1 Phoenix, Ariz. 3,324,363 6/1363 Hillet a]. 1012/55/83? [211 App]. No. 779,120 3,487,986 1 l 7 Nelson eta. [22] Filed Nov. 26, 1968 Patented Jan. 5 1971 Przrnary Examiner William B. Penn A west Elm C In ted Assistant ExammerE. M. Coven [73] Sslgnee N w $31 N Y ompany corpora Attorneys-H. J. Winegar, R. P. Miller and A. C. Schwarz, Jr.

a iorporation of New York TRA T: I h [54] SYNCHRONIZING THE MOVEMENT OF FIRST s e find ar t icles stfzl i as t ii fig zd3:23 12 first and ac eted cable) AND SECOND ARTICLES AND PRINTING IN and a rotatable printing wheel mechanism for printing M S S 9 THE ARTICLES markings on the strand at accurately spaced intervals, the l Clams raw 2 printing wheel mechanism is rotatably driven by a variable [52] 11.8. CI 101/37, speed drive mechanism. The variable speed drive mechanism 101/74; 101/248; 226/42 and a strand advancing mechanism drive respective signal [51] Int. Cl. .4 ..B4lf 17/10, generating devices, the signals of which are compared to 1341f 13/ 12: B65h 23/ 18 produce a coarse analog control signal representative of any [50] Field of Search l0l/36, 37, difference therebetween. Similarly, the variable speed drive 219, 226, 227, 228, 248, 181, 73, 74, 75; 226/29, mechanism and a rotatable control member which is rotatably 30, 42; 242/75;318/6, 7, 329, (Inquircd) driven through frictional engagement with the advancing strand, drive digital signal generating devices, the signals of [56] References c'ted which are compared and used to produce an overriding fine N TE STATES PATENTS analog control signal representative of any difierence be- 2,169,0l6 8/1939 Baker 242/75 tween them. The coarse and fine analog control signals then 2,739,528 3/ 1956 Lowe 101/37 are combined to produce a signal for controlling the speed 2,963,555 12/1960 Brubaker 226/42X of the variable speed drive mechanism, and thus of the print- 3,l65,056 1/ 1965 Heatley et al 226/42X ing wheel mechanism.

z I a7 2\ an, u l 'Q 31a I Y \A// Ag it I 39 JUL 23 i a? Z9 Z7 1 E. C. E. C. A. C.

CLUTCH BRAKE MOTOR JUL JUL ru M ADD-SUB.D1G. 4 CTR. AND D/A COMPARATOR REGULATOR CONVERTER N N J'LI'L D.C. AMPLIFER PATENTEDJAN 97l EMnZJQEQAYO \NVENTOR R1: MlNEHART fifi M ATTORNEY slippage therebetween.

1 SYNCHRONIZING THE MOVEMENT OF FIRST AND SECOND ARTICLES AND-PRINTING'MARKINGS ON ONE OF THE ARTICLES BACKGROUND OF THE INVENTION measuring the length ofa longitudinally advancing jacketed communication cable and for printing sequential footage markings on the jacket of the cable.

2. Description of the Prior Art In the manufacture of communication cable, it is standard practice to advance the cable from a supply reel through apparatus for extruding a plastic jacket on the cable, and subsequently to wind the jacketed cabl'eon a reel by a takeup mechanism/After the jacket has been applied to the cable and as it proceeds to the takeup mechanism, it passes through apparatus for measuring its length and for printing sequential footage markings on the jacket. The sequential footage markings, in addition to indicating the amount of cable on the reel, are used where the cable subsequently is cut into shorter sections, to determine the location at which the cable should be cut to obtain a section of a desired length and to indicate the amount of cable which still remains on the reel after a section has been removed therefrom.

I-Ieretofore, various apparatus for measuring the length of the cable and for printing the sequential footage markings thereon have been proposed. For example, apparatus is known in which a measuring and printing wheel mechanism has its periphery frictionally engaged with the longitudinally advancing cable so that it is'rotatably driven by the cable. In

other known apparatus, a printing wheel mechanism rides in peripheral engagement with the cable, but one or more drive wheels are driven by the cable through frictional engagement therewith and these wheels then drive the printing wheel mechanism through a suitable drive system. In certain apparatus -of this type, in order that the printing wheel mechanism will exert no drag on the cable and, cause slippage between the printing wheel mechanism and the cable, the

- printing wheel mechanism is rotatably driven by a motor an amount sufficient to overcome the effect of friction in the mountings for the printing wheel mechanism. Frequently, pressure rollers are used to urge the cable against the printing wheel and/or the drive wheels so as to increase the frictional resistance between the cable and the wheels and to reduce Apparatus as above-described have not proven satisfactory in the past because the measurement of the cables length and the sequential footage markings'printed on the cable have been found to be inaccurate. Accordingly, to insure that the required footage of cable was actually wound on'each reel it was necessary to utilize a relatively large safety factor and to wind an amount of cable on each reel in excess of the amount required on the reel.

This procedure is undesirable because in many instances the cumulative error actually made by the measuring apparatus is less than the maximum expected error by a significant amount, and thus many of the reels have lengths of cable thereon considerably in excess of the amount required. This excess cable, while contributing to production costs, cannot be considered as part of the actual production, thus increasing the cost of manufacture of the cable substantially, particularly where a considerable amount of cable is being manufactured. Further, since the sequential footage markings printed on the cable are inaccurate, they cannot'be relied upon to indicate the actual cable footage on a reel, to determine the location at which the cable on a reel should be cut to produce a cable section of a desired length, or to indicate-the amount of cable remaining on a reel after a section has been cut therefrom.

SUMMARY OF THE INVENTION An object of the invention is to provide a new and improved method and apparatus for synchronizing the movement of a first article and a second article.

A further object of the invention is to provide a new and improved method and apparatus for synchronizing the movement of a rotating member and a linearly moving article.

A still further object of the invention is to provide a new and improved method and apparatus for synchronizing the movement of a rotating member and a longitudinally advancing strand. I

Another object of the invention is to provide a new and improved method and apparatus for measuring the length of a longitudinally advancing strand and marking the strand at preselected accurately spaced intervals.

In accordance with the invention, synchronizing the speed of movement of a first article and a second article involves generating a coarse analogue control signal representative of any difference between the speeds of a power driven means 7 for causing movement of the first article and a variable speed drive means for causing movement of the second article, and generating an overriding fine analogue control signal representative of any difference between the speed of the variable speed drive means and the speed of a control member being driven in response to the actual speed of the first article. The coarse and fine analogue control signals then are combined to produce a signal for controlling the speed of the variable speed drive means, and thus the speed of movement of the second article.

More specifically, measuring the length of a continuously advancing strand and printing markings on the strand at accurate'ly spaced intervals with a rotatable printing wheel mechanism involves generating a coarse analogue control signal representative of any difference between the speed of a strand advancing means and a variable speed drive means for rotating the printing wheel mechanism. Further, a digital signal representative of the speed of a control wheel which is rotatably driven by the longitudinally advancing strand through frictional engagement therewith, and a digital signal representative of the rotational speed of the variable speed drive means, are compared and utilized to generate an overriding fine analogue control-signal representative of any difference therebetween. The coarse and fine analogue control signals then are combined to produce a signal for controlling the rotational speed of the variable speed drive means, and thus of the printing wheel mechanism.

BRIEF DESCRIPTION OF THE DRAWING DETAILED DESCRIPTION FIG. 1 of the drawing shows the invention as applied to the measuring of the length of a continuous strand in the form of a jacketed communication cable 11, and to the printing of sequential footage markings 12 on the cable as illustrated in FIG. 2.

The cable 11 is advanced from left to right in FIG. 1 from a supply reel (not shown) and through an extruder (not shown) for extruding a plastic jacket thereon, by a tractor-type capstan l3. Ultimately, the jacketed cable 11 is wound on a takeup reel 14 by a power driven takeup mechanism 16. The capstan 13 is conventional in nature and preferably is provided with slip clutches to preclude damage to the cable in the event that the takeup mechanism 16 should overdrive the capstan.

' parator.

Between the capstan 13 and the takeup mechanism 16 the jacketed cable 11 passes through a mechanism 17 for printing the sequential footage markings 12 on the jacket of the cable asindicated in FIG. 2. The mechanism 17 includes a printing wheel 18 having a printing head 19 incorporated therein and rotatable therewith, and the printing wheel is connected to drive a footage counter 21, in a manner well-known to those skilled in the art. The mechanism 17 also includes an upper set of rotatably mounted cable guideidler wheels 22 and a lower set of rotatably mounted cable support idler wheels 23. The

'support wheels 23 are movable vertically in any suitable manner between a lower position as shown in dashed lines in 7 FIG. 1, in which the cable 11 can be strung over them, andan speed drive 24, through a suitable gear reduction system 26. In

the illustrated embodiment of the invention, the variable speed drive 24 is shownasincluding an AC motor 27, an eddy current clutch 28 and an eddy current brake 29; In the alternative, the variable speed drive 24 could be aDC motor having its armature current and field excitation regulated to control its speed in a well-known manner.

The speed of the drive 24, and thus of the printing wheel 18, is controlled by a regulator circuit 30 connected to feed a speed increase or a speed decrease signal to the drive. In this connection, the eddy current brake 29 of the drive 24pmvides rapid deceleration of the printing wheel 18 when a speed decrease signal is received from theregulator 30 and provides close regulation of the printing wheels speed during normal running conditions. The speedincrease or speed decrease signal for the drive 24 is produced by the regulator 30 in response to a coarse analogue control signal from a comparator circuit 31 and/or a fine analogue control signal from a composite add-subtract digital counter and digital to analogue converter circuit 32, with any fine analogue control signal from this counterconverter circuit being amplified so as to override any coarse analogue control signal from the com- The comparator 31, which may be of any suitable type, forms a part of a feedback system which also includes a first tachometer generator 33 (master) driven by capstan l3, and a second tachometer generator 34 (slave) driven by the variable speed drive 24 through the gear reduction system 26. The reference signal from the first tachometer generator 33; which is representative of the drive speed of the capstan 13, and the feedback signal from the second tachometer generator 34, which is-representative of the rotational speed of the variable speed drive 24, both feed to the comparator 31. The comparator 31 detects any difference between the two signals and produces a coarse analogue control signal which is representative of the difference and which feeds to the regulator 30;

. The fine analogue control signal is produced by a system which includes a master reference or control wheel 36, preferably of the same circumference as the printing wheel 18, and having its periphery tangentially engaged with the advancing jacketed cable 11 so that it is rotatably driven by the cable through friction. To maintain the master control wheel 36' and the jacketed cable 11 in vertical alignment and to preclude slippage therebetween, the cable travels through a guide assembly 37 and the master control wheel is suitably biased into engagement with the cable from above in any suitable manner.

The guide assembly 37 includes a horizontally extending support 370 and a pair of guide rollers 37b (only one shown) arranged to form a V-shaped nest in which the cable is received. As the master control wheel 36 is rotated by the jacketed cable 11 it drives a footage counter 38 in a manner wellknown to those skilled in the art.

The master control wheel 36 also drives a first rotary transducer 39 (master) which generates impulses to provide a digital signal represeri'ta'ti 6f the rotational speed atfwhich the master control wheel is being driye'nby the advancing jacketed cable 11. Similarly, the variable speed drive 24, through the the gear reduction system 26, drives a second rio} tary transducer 41 (slave) which 'g'ene rates'impulses to pro} vide a digital signal representative of thfirotatibnals'peed of the drive, and thus of the printingavheel 1811 11: digital signals feed to the composite counterconverter circuit;3L 1

The composite counterconverten-circuit 32 provides'a pulse to pulse comparison of the digital isignalsgto determine whether the impulses being received from'the secondrotary transducer 41 are the same as, less than,:or greater than'the impulses being received from the first rotary transducer 39 and produces a resultant fine analogue control "signal representative of any difference. In this connection, impulses from the two rotary transducers 39 and 41 are counted and compared in a suitable add-subtract digital counter portionof the composite counterconverter circuit 32, thus eliminating the need for a time base in establishing an error signal. (The resultant error signal from the add-subtract digital counter portion of the counterconverter circuit 32 then is transformed into the fine analogue control signal in a digital to analogue converterport'ion of thecounterconverter circuit. The'fine analogue control signal 'will be of positive or negative polarity, depending on whether the slave rotary transducer 41' is producing more or less impulses than the master rotary transducer 39, respectively, and will continue tobe produced until the impulses fromthetwo rotary transducers are equal. 1

The fine analogue control signal isfed tothe drive regulator 30 through a suitable DC amplifier 42 which amplifies ,the

signal so that it will override any coarseianalogue .control signal being received by theregulator from theicomparator 31. In this connection, if the impuls'esfrom' the slave rotary transducer 41 exceed those from the master -rotaryitransducer 39, the variable speed drive 24 is running too 'fastiand'the composite counterconverter circuit 32 produces a *signaiaot proper polarity callingfor a decrease in the drives speed, whereas if the impulses from the slave rotary transducer are less than those from the master rotary transducenthe drive is running too slow and the composite counterconverterycircuit produces a signal of proper polarity calling for an increase -in the drives speed. If the number of impulses from the .two. r0"- tary transducers 39-and 41. is the same,the compositecounterconverter circuit 32 :Iproduces no signal atits output and the variable speed drive 24 continues to run at its existing speed,

The drive regulator 30, which is responsive to the coarse and fine analogue control signals from the comparator 31 and the composite counterconverter circuit 32 to produce the speed increase and speed decrease signals for the variable speed drive 24, may be of a conventional .type such as the Model MD-2CB controller of the Louis Allis Company of Milwaukee, Wisconsin, and the composite counterconverter circuit 32 may be the Model 18 D40 unit (known as a digital ratio controller") of the Dynapar'Corporation of Gurnee,.ll

linois. 1 As is shown in FIG. 2, the illustrated embodiment of the invention is designed to produce the sequential. footage markings 12 on the cable 11 every 2 feet, and for this purpose the printing wheel '18 and the master control wheel 36 preferably are both 2 feet in circumference. With wheels 18 and 36 0f this size, favorable results in measuring and marking accuracy. have beenachieved'with the rotary transducers 39 and 41-set to produce 1200 impulses per revolution (600impulses per foot). In the event that the circumference of the master control wheel 36 is not exactly equal to thedesired marking interval (such as 2 feet) the accuracy of the system can be improved by programming a compensating error count verter circuit 32.

, OPERATION In operation, the cable 11 is advanced from left to right in FIG. 1 by thecapstan 13 and subsequently is wound on the takeup reel 14 by the takeup mechanism 16. At the same time the printing wheel 18 of the printing mechanism 17 is rotatably driven by the variable speed drive 24 through the gear reduction system 26.

lower support wheels 23, in cooperation with the upper guide wheels 22, maintain the cable in tangential engagement with the printing wheel 18 so that'upon each revolution of the wheel the'printing head 19. carried therein prints a footage marking 12 on the cable as shown in FIG. 2.

To produce the coarse analogue control signal for the variable speed drive 24, the capstan 1am addition to advancing the cable 11, drives the first tachometer generator 33 to pro-- 1 vide an analogue reference signal representative of the driving speed of the capstan. Similarly, the variable speed drive 24, in addition to'rotating the printing wheel 18, drives the second tachometer generator 34 through the gear reduction system 26 to provide an analogue feedback signal representative of the driving speed of the variable speed drive, and thus of the rotational speed of the printing wheel. These signals bothfeed to the comparator 31 which 'detectsany difference between them and generates a coarse analogue control signal representative ofthe difference, the coarseanalogue control signal then feeding to the drive'regulator 30.

To produce the fine analogue control signal for the variable speed drive 24, themaster control wheel 36 drives the first ro-- tary transducer 39, which generates impulses to provide a digital signal representative of the speed at which the master control wheel is being rotatably driven by the cable 11. Similarly, the variable speed drive 24, which is driving the printing wheel 18 and the first tachometer generator 34 through the gear reduction system 26, also drives the second rotary transducer 41*through the gear reduction system. The

. rotary transducer 41 generates impulses to provide a digital signal representative of the driving speed of the variable speed drive 24, and thus of the rotational speed of the printing wheel 18. The digital signals both feed to the composite countercon- If the composite counterconverter circuit 32 detects that a difference of one or more impulses exists between the digital signals from the rotary transducers 39 and 41, .it produces a fine analogue control signal representative of the difference. This control signal then feeds from the output of the composite counterconverter circuit 32 to the drive regulator through the DC amplifier 42 and overrides any coarse analogue control signalbeing received by the regulator fromthe comparator 31. g Y 1 The drive regulator 30, in response to any coarse and fine analogue control signals received from the comparator 31 and the composite counterconverter circuit 32, produces an analogue speed increase or speed decrease signal, as the case may be, which signal then is fed to the variable speed drive 24. When the variable speed drive 24 receives a speed decrease signal from the regulator 30, the eddy current brake 29 helps insure greater printing accuracy by providing fast deceleration of the drive and the printing wheel 18.

During the measuring and printing operation, the printing wheel 18 drives the footage counter 2i and the master control wheel 36 drives the footage counter 38. The readings on the footage counters 21 and 38, in addition to providing an indication of when the required length of the'cable 11 has been wound on the reel 14, can be compared during and at the end of a cable run and used as a check on whether the measuring and printing system is functioning accurately.

lclaim:

1. The method of synchronizing the speed of movement of a first article and a second article, which comprises:

generating a coarse analogue control signal representative of any difference which may occur between the driving speed of a drive means for moving the first article and a drive means for moving the second article;

driving a control member in response to the actual speed of movement of the firstarticle;

generating a'fine analogue control signal which is representative of any difference which may occur between the speed of the control member and the driving speed of the drive means for moving the second article, and which is of a magnitude such that it will override any coarse analogue control signal; and producing an analogue control signal representative of the combined coarse and fine analogue control signals to control the driving speed of the drive means for moving the second article. 0 2. The method of synchronizing the speed of movement of a first article and a second article, as recited in claim 1, in which the first article is an elongated longitudinally moving strand and the control member is positioned in frictional engagement with the strand so that it is driven by the strand.

3. The methodof synchronizing the speed of movement of a first article and a second article, as recited in claim 1, in which the generation of the fine analogue control signal includes:

generating a digital signal representative of the speed of the control member; generating a digital signal representative of the driving speed of the drive means for moving the second article;

i and comparing the digital signals and producing an analogue signal representative of any difference therebetween.

4. The method of marking an article, which comprises:

advancing the article adjacent a rotatable marking mechanism;

generating a coarse analogue control signal representative of any difference which may occur between the driving speed of an advancing means for the article and a drive means for the rotatable marking mechanism; driving a control member in response to the actual speed of the advancing article;

generating a fine analogue control signal which is representative of any difference which may occur between the speed of the control member and the driving speed of the drive means for the rotatable marking mechanism, and which is of a magnitude such that it will override any coarse analogue control signal; and

producing an analogue control signal representative of the combined coarse and fine analogue control signals to control the driving speed of the drive means for the rotatable marking mechanism.

5. The method of marking an article, as recited in claim 4, in which the article is an elongated strand which is to be marked at accurately spaced intervals and in which the control member is positioned in frictional engagement with the advancing strand so that it is driven by the strand.

6. The method of marking an article, as recited in claim 4, in which the generation of the fine analogue control signal includes:

generating a digital signal representative of the speed of the control member;

generating a digital signal representative of the driving speed of the drive means for moving the second article; and

comparing the digital signals and producing an analogue signal representative of any difference therebetween.

7. Apparatus for synchronizing the speed of movement of a first article and a second article, which comprises:

power driven means for causing movement of the first article;

variable speed drive means for-causing movement of the second article;

first signal producing means for producing a coarse analogue control signal representative of any difference between the speed of said power driven means and said variable speed drive means;

a control member driven in response to the actual speed of movement of the first article; second signal producing means for producing a fine analogue control signal representative of any difference between the speed of said control member and the speed of said variable speed drive means and of a magnitude such that it will override any coarse analogue control signal produced by said first signal producing means; and

means for controlling the speed of said variable speed drive means and thus of the movement of the second article, said controlling means being responsive to any coarse and fine analogue control signals produced by said first and second signal producing means.

8. Apparatus for synchronizing the speed of movement of a first article and a second article, as recited in claim 7, in which:

said first signal producing means includes-signal generating devices driven by said power driven means and said variable speed drive'means; and

said second signal producing means includes digital signal generating devices driven by said control member and said variable speed drive means. v

9. Apparatus for synchronizing the speed of movement of a first article and a second article, asrecited in claim 7, in which the second article is a rotatable member and in which:

said power driven means moves the first article in a linear patlr;and

said variable speed drive means rotates the second article.

1.Apparatu; for synchronizing the speed of movement of l a first article and a second article, as recited in claim 7, in which the first article is an elongated continuous strand and in which:

said power driven means moves the strand longitudinally;

and said control member is rotatable and is rotatably driven by the longitudinally moving strand through frictional engagement therewith. 11. Apparatus for synchronizing the speed of movement of a first article and a second article, as recited in claim 7, in which the first article is an elongated continuous strand, in which the second article is a rotatable member of a preselected circumference having its periphery engaged with the strand, and in which:

said power driven means advances the strand longitudinally; said variable speed drive means rotates the second article;

and said control member is a rotatable member having a preselected circumference and having its periphery frictionally engaged with the longitudinally advancing strand whereby said control member is rotatably driven by the strand. 12. Apparatus for marking an article, which comprises: power driven means for advancing the article; a rotatable article marking mechanism; variable speed drive means for rotating said article marking mechanism; first signal producing means for producing a coarse analogue control signal representative of any difference between the speed of said article advancing means and the rotational speed of said variable speed drive means; a control member driven in response to the actual speed of advancement of the article; second signal producing means .for producing a fine analogue control signal representative of any difference between the speed of said control member and the rota tional speed of said variable speed drive means, and of a magnitude such that it will..override any coarse analogue control signal produced by said first signal-xproducing means; and g means for controlling the rotational speed of said variable speed drive means and thus of said article marking mechanism, said controlling means "being-responsive to any coarse and fine analogue control signs spro'du'ced by said first and second signal produci ngmeans 13. Apparatus for marking an article,- as recited in clairnll, inwhich: I said first signal producing means inchide's "sig'iia'l devices driven by said article adva'ningmeansand said variable speed drive means; and 1 f'- said second signal producing means includes digital signal generating devices driven by said control inembe'r and said variable speed drive means. 14. Apparatus for marking an article, as recited in claim- 12, in which the article is an elongated continuous strand which is to be marked at accurately spaced intervals, and in which:

said article advancing means advances the elongated strand longitudinally; and said control member is rotatable and is rotatably driven by the longitudinally advancing strand through frictional engagement therewith. 15. Apparatus for marking an article, as recited in claim 12, in which the article is an elongated continuous strand which is to be marked at accurately spaced intervals, and in which:

said article advancing means advances the strand longitudinally; said rotatable article marking mechanism includes a printing head carried by a printing wheel having a preselected circumference and having its periphery engaged with the longitudinally advancing strand; and said control member is a? rotatable wheel having a preselected circumference and having its periphery fric tionally engaged with the longitudinally advancing strand whereby it is rotatably driven by the strand,

16. Apparatus for marking an article, as recited in claim 12, i

first and second signal generating devicesdrivenby the first I strand advancing means and said variablespeed drive means, respectively, to produ Sfipara'te signals representative of the speed of the first strand advancing means and the rotational speed of said variable speed drive means; v 1 first circuit means forcomp'aring the signals from first and second signal generating devices and for producing a Q coarse analogue control signal representative of any difference between the signals;

a master control wheel of a preselected circumference and having'its periphery frictionally engaged withQtlie advanc-s ing strand whereby it is rotatably driven by the advancing strand;

-first and signal generating device v drivenf by said master control'wheeland said variable speed drive means for the printing whe el mechanism, respectively, to produce separatefdigital signals representative of the rotational speeds of said master .control wheel and said' variable speed drive means for the printing wheel mechanism;

second rcircuit means for comparing thedigital signals and for converting any difference between the-digital signals "to a fine analogue control signal which is representative of the difference and which is of a magnitude such that it mechanism, said controlling means being responsive to any coarse and fine analogue control signals produced by said first signal comparing circuit means and said digital to analogue signal converting means.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PatemNo. 3.552.308 Dated lamlflly 5 19 1 Inventor(s) R. F. Minehart It is certified that error appears in the above-idenrified parent and that said Letters Patent are hereby corrected as shown below:

Column I line 14., omit "the" on second occurrence. Column 6, line 66, "moving the second article" should read -the rotatable marking meohanism.

Signed and sealed this 29th day of June 1 971 (SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER JR Attesting Officer Commissioner of Patents 

1. The method of synchronizing the speed of movement of a first article and a second article, which comprises: generating a coarse analogue control signal representative of any difference which may occur between the driving speed of a drive means for moving the first article and a drive means for moving the second article; driving a control member in response to the actual speed of movement of the first article; generating a fine analogue control signal which is representative of any difference which may occur between the speed of the control member and the driving speed of the drive means for moving the second article, and which is of a magnitude such that it will override any coarse analogue control signal; and producing an analogue control signal representative of the combined coarse and fine analogue control signals to control the driving speed of the drive means for moving the second article.
 2. The method of synchronizing the speed of movement of a first article and a second article, as recited in claim 1, in which the first article is an elongated longitudinally moving strand and the control member is positioned in frictional engagement with the strand so that it is driven by the strand.
 3. The method of synchronizing the speed of movement of a first article and a second article, as recited in claim 1, in which the generation of the fine analogue control signal includes: generating a digital signal repResentative of the speed of the control member; generating a digital signal representative of the driving speed of the drive means for moving the second article; and comparing the digital signals and producing an analogue signal representative of any difference therebetween.
 4. The method of marking an article, which comprises: advancing the article adjacent a rotatable marking mechanism; generating a coarse analogue control signal representative of any difference which may occur between the driving speed of an advancing means for the article and a drive means for the rotatable marking mechanism; driving a control member in response to the actual speed of the advancing article; generating a fine analogue control signal which is representative of any difference which may occur between the speed of the control member and the driving speed of the drive means for the rotatable marking mechanism, and which is of a magnitude such that it will override any coarse analogue control signal; and producing an analogue control signal representative of the combined coarse and fine analogue control signals to control the driving speed of the drive means for the rotatable marking mechanism.
 5. The method of marking an article, as recited in claim 4, in which the article is an elongated strand which is to be marked at accurately spaced intervals and in which the control member is positioned in frictional engagement with the advancing strand so that it is driven by the strand.
 6. The method of marking an article, as recited in claim 4, in which the generation of the fine analogue control signal includes: generating a digital signal representative of the speed of the control member; generating a digital signal representative of the driving speed of the drive means for moving the second article; and comparing the digital signals and producing an analogue signal representative of any difference therebetween.
 7. Apparatus for synchronizing the speed of movement of a first article and a second article, which comprises: power driven means for causing movement of the first article; variable speed drive means for causing movement of the second article; first signal producing means for producing a coarse analogue control signal representative of any difference between the speed of said power driven means and said variable speed drive means; a control member driven in response to the actual speed of movement of the first article; second signal producing means for producing a fine analogue control signal representative of any difference between the speed of said control member and the speed of said variable speed drive means and of a magnitude such that it will override any coarse analogue control signal produced by said first signal producing means; and means for controlling the speed of said variable speed drive means and thus of the movement of the second article, said controlling means being responsive to any coarse and fine analogue control signals produced by said first and second signal producing means.
 8. Apparatus for synchronizing the speed of movement of a first article and a second article, as recited in claim 7, in which: said first signal producing means includes signal generating devices driven by said power driven means and said variable speed drive means; and said second signal producing means includes digital signal generating devices driven by said control member and said variable speed drive means.
 9. Apparatus for synchronizing the speed of movement of a first article and a second article, as recited in claim 7, in which the second article is a rotatable member and in which: said power driven means moves the first article in a linear path; and said variable speed drive means rotates the second article.
 10. Apparatus for synchronizing the speed of movement of a first article and a second article, as recited in claim 7, in which the first article is an elongated Continuous strand and in which: said power driven means moves the strand longitudinally; and said control member is rotatable and is rotatably driven by the longitudinally moving strand through frictional engagement therewith.
 11. Apparatus for synchronizing the speed of movement of a first article and a second article, as recited in claim 7, in which the first article is an elongated continuous strand, in which the second article is a rotatable member of a preselected circumference having its periphery engaged with the strand, and in which: said power driven means advances the strand longitudinally; said variable speed drive means rotates the second article; and said control member is a rotatable member having a preselected circumference and having its periphery frictionally engaged with the longitudinally advancing strand whereby said control member is rotatably driven by the strand.
 12. Apparatus for marking an article, which comprises: power driven means for advancing the article; a rotatable article marking mechanism; variable speed drive means for rotating said article marking mechanism; first signal producing means for producing a coarse analogue control signal representative of any difference between the speed of said article advancing means and the rotational speed of said variable speed drive means; a control member driven in response to the actual speed of advancement of the article; second signal producing means for producing a fine analogue control signal representative of any difference between the speed of said control member and the rotational speed of said variable speed drive means, and of a magnitude such that it will override any coarse analogue control signal produced by said first signal producing means; and means for controlling the rotational speed of said variable speed drive means and thus of said article marking mechanism, said controlling means being responsive to any coarse and fine analogue control signals produced by said first and second signal producing means.
 13. Apparatus for marking an article, as recited in claim 12, in which: said first signal producing means includes signal generating devices driven by said article advancing means and said variable speed drive means; and said second signal producing means includes digital signal generating devices driven by said control member and said variable speed drive means.
 14. Apparatus for marking an article, as recited in claim 12, in which the article is an elongated continuous strand which is to be marked at accurately spaced intervals, and in which: said article advancing means advances the elongated strand longitudinally; and said control member is rotatable and is rotatably driven by the longitudinally advancing strand through frictional engagement therewith.
 15. Apparatus for marking an article, as recited in claim 12, in which the article is an elongated continuous strand which is to be marked at accurately spaced intervals, and in which: said article advancing means advances the strand longitudinally; said rotatable article marking mechanism includes a printing head carried by a printing wheel having a preselected circumference and having its periphery engaged with the longitudinally advancing strand; and said control member is a rotatable wheel having a preselected circumference and having its periphery frictionally engaged with the longitudinally advancing strand whereby it is rotatably driven by the strand.
 16. Apparatus for marking an article, as recited in claim 12, which further comprises: brake means for causing quick deceleration of said rotatable article marking mechanism.
 17. In apparatus for measuring the length of an elongated strand and printing markings on the strand at accurately spaced intervals, in which the strand is advanced longitudinally by first power driven means and subsequently by a power driven takeup mechanism, and in which a rotaTable printing wheel mechanism is engageable with the advancing strand to print the markings thereon, the improvement which comprises: variable speed drive means for rotating the printing wheel mechanism; first and second signal generating devices driven by the first strand advancing means and said variable speed drive means, respectively, to produce separate signals representative of the speed of the first strand advancing means and the rotational speed of said variable speed drive means; first circuit means for comparing the signals from said first and second signal generating devices and for producing a coarse analogue control signal representative of any difference between the signals; a master control wheel of a preselected circumference and having its periphery frictionally engaged with the advancing strand whereby it is rotatably driven by the advancing strand; first and second digital signal generating devices driven by said master control wheel and said variable speed drive means for the printing wheel mechanism, respectively, to produce separate digital signals representative of the rotational speeds of said master control wheel and said variable speed drive means for the printing wheel mechanism; second circuit means for comparing the digital signals and for converting any difference between the digital signals to a fine analogue control signal which is representative of the difference and which is of a magnitude such that it will override any coarse analogue control signal produced by said first signal comparing means; and means for controlling the rotational speed of said variable speed drive means and thus of the printing wheel mechanism, said controlling means being responsive to any coarse and fine analogue control signals produced by said first signal comparing circuit means and said digital to analogue signal converting means. 